The present invention relates to an electrical cable connector which is used for electrical connection of a cable and a circuit board, a cable and a cable, and so on.
Such electrical cable connectors have been available in various types. All of such connectors are designed such that each of the contacts constituting a connector must be connected to a core wire of a respective cable. As conventional methods for connecting the contacts of the connector to the core wires of the cables, crimping, clamping, wire soldering, etc. are well known.
Connection by crimping is performed by enclosing a respective cable with the protruding ends of each contact. If such a crimping is to be applied in the cable connection of a multiple terminal connector, which comprises a plurality of contacts aligned in a housing, then it is difficult to make the pitch of the contact alignment substantially small to realize a miniaturized connector.
Connection by clamping is performed by lancing the insulation of the core wire of a cable with a clamping portion that is provided in a contact and by holding the core wire with the clamping portion. Because of the way clamping is performed, there is a concern that the core wire may be damaged or cut during the clamping. Especially, when contacts are provided at a relatively small pitch as in a miniaturized connector with multiple terminals which is offered by the latest technology, because the cables as well as the core wires to be connected are very thin, there is a high possibility that the core wires may be damaged or cut during the clamping.
On the other hand, connection by wire soldering is not prone to cause the above mentioned problems. However, soldering the core wires one by one costs a substantial production cost. Especially, as the multi-terminalization of connectors progresses, the contact alignment pitch will become even smaller, so not only the production cost (labor hours) but also requirements for precision and reliability in the soldering are expected to increase further.
It is an object of the present invention to provide an electrical cable connector whose construction enables soldering of a plurality of contacts to the core wires of a plurality of cables in a single soldering step.
It is another object of the present invention to provide an electrical cable connector which is easy to perform the above mentioned soldering process and which offers a high reliability for the soldering connection.
It is yet another object of the present invention to provide an electrical cable connector which is suitable for connection of a plurality of coaxial cables.
It is still another object of the present invention to provide an electrical cable connector whose construction enables electrical grounding of the shielding layers of a plurality of coaxial cables in a lump.
To achieve these objectives, an electrical cable connector according to the present invention comprises a plurality of contacts, which are aligned and retained in a retaining member made of an electrically insulative material. Each of the contacts includes a cable connection portion with an upper surface, onto which a core wire of each cable is soldered. The retaining member includes a plurality of receiving grooves, which are provided in alignment in a plane to receive, align and retain the cable connection portions of the contacts, respectively. When the cable connection portions of the contacts are received and retained in the receiving grooves, and when the core wires are mounted on the upper surfaces of the cable connection portions, respectively, the upper ends of the core wires are positioned evenly above the plane in which the receiving grooves are provided.
In this cable connector, the upper ends of all the core wires, which are placed on the cable connection portions that are retained in the receiving grooves, respectively, are positioned evenly. Therefore, by bringing the heating surface of a pulse heater into contact to heat the core wires, all the core wires are soldered in a single soldering step to the cable connection portions of the contacts, respectively.
Preferably, all of the receiving grooves have an identical depth which is greater than the thickness of the cable connection portions. As a result, when the cable connection portions are received and retained in the receiving grooves, the upper surfaces of the cable connection portions are positioned below the surfaces of the receiving grooves (i.e., below the plane in which the receiving grooves are provided). Thus, the core wires are placed respectively in the concaves which are defined by the sides of the receiving grooves and the upper surfaces of the cable connection portions. This construction makes the placing and positioning of the core wires simple and precise.
The above mentioned cables can be coaxial cables, each comprising a core wire, an inner insulating layer, which covers the core wire, an electrically conductive shielding layer, which covers the inner insulating layer, and an outer insulating layer, which covers the electrically conductive shielding layer. In this case, a plurality of coaxial cables are stripped of the outer insulating layers to expose the electrically conductive shielding layers and are aligned to one another. Then, by sandwiching the exposed electrically conductive shielding layers with two electrically conductive binding plates, these coaxial cables are aligned and retained in a plane. In this condition, the core wires, which are aligned and are exposed at the end portions of the coaxial cables beyond the portions that are sandwiched by the electrically conductive binding plates, are placed and then soldered in a single soldering step easily and precisely onto the upper surfaces of the cable connection portions, which are retained in the receiving grooves.
Preferably, the portions of the coaxial cables between the portions where the core wires are exposed and the portions which are sandwiched by the electrically conductive binding plates are stripped of the outer insulating layers and of the electrically conductive shielding layers to expose the inner insulating layers, and these portions, where the inner insulating layers are exposed, are bent in a U or V shape to provide slacks. This construction prevents any external force acting on the cables from accidentally affecting the soldered portions between the core wires and the cable connection portions because such external forces can be cushioned by these slacks. Also, this construction can effectively prevents any external force which may be created from displacement of the electrically conductive binding plates from affecting the soldered portions because the slacks can absorb such displacement.
In addition, this cable connector is provided with a metallic cover to cover the retaining member and the electrically conductive binding plates. Preferably, the electrically conductive binding plates are maintained in contact with the metallic cover to establish an electrical connection. Furthermore, when this connector is engaged with an matable connector, the metallic cover comes into contact with a grounding member which is provided in the matable connector. Thereby, an electrical grounding connection is established when the connectors are engaged. In this construction, the electrically conductive binding plates are fixed and retained in the cover to prevent any external force from accidentally affecting the soldered portions between the core wires and the cable connection portions, and the shielding layers of the cables are grounded electrically through the electrically conductive binding plates and the metallic cover.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.